In converged transport architectures, Ethernet frames (specifically, layer 2 or L2 Ethernet frames) are transparently transported using a wide range of optical-based transport networks, such as synchronous optical networking (SONET), Optical Transport Network (OTN, or Packet over Optical Channel Data Unit (ODU)), Dense Wavelength Division Multiplexing (DWDM), and so forth.
Protocols for the converged transport architectures can require a phase-locked reference clock that is common to multiple network elements. For example, in OTN Over Packet Fabric Protocol, a 311.04 megahertz (MHz) common reference clock is phase-locked to a common time-stamp synchronization pulse of 8 kilohertz (kHz). For an individual network element, maintaining phase synchronization may be achieved by controlling the clock signal routing delay skews. However, maintaining phase synchronization is more complex for a communication system having multiple network elements, which in some cases may require accuracy on the order of nanoseconds. For example, factors such as component variations and/or temperature variations of the different network elements, as well as the properties of cabling connecting the different network elements, can affect the amount of delay of the phase synchronization pulse.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.